This section is from the book "Commercial Gardening Vol4", by John Weathers (the Editor). Also available from Amazon: Commercial Gardening, A Practical & Scientific Treatise For Market Gardeners.
It is worth while giving a little attention to the condition of the spawn; for a hot or wet bed hard cakes do best; for a cold or dry bed, green or soft cakes should be chosen. Cheap spawn is not necessarily cheapest in the end. Good spawn costs very little more per house, and usually makes a great deal of difference to the crop, not only as regards quantity, but also in quality. It is usual to break the cakes into six pieces, but the best quality can be broken into eight; the larger the piece the less risk of all the spawn being killed. Before proceeding to lay out the latter the bed should be levelled over, testing to see that the depth is equal. The spawn should be laid out in lines 10 in. apart both ways, from centre to centre, using marked boards for the purpose. The only tool needed for spawning is a dagger-shaped piece of wood. This is inserted at an angle of about 45 degrees, the manure lifted up, and the piece of spawn put in, outside edge upwards, and about 1 in. below the surface. The bed is firmly trodden as the work proceeds, and it will be found that a large area can be spawned in a short time. If the bed should be too wet, each piece of spawn should have some dry sweet droppings tucked in all round it, to help absorb the moisture - dry, half-rotted litter, or even hay twisted round the cake, will answer the purpose. If the outer surface of the cake once damps, the mycelium or spawn will not be able to get through to the bed.
Fig. 479. - A "cake" or "brick" of Mushroom Spawn.